Biotin-conjugated IgG fraction of polyclonal goat antiserum to rat IgG, IgA and IgM, heavy and light chains, adsorbed for human and mouse cross-reactivity. In immunocytochemical and immunohistochemical staining of monoclonal rat monoclonal antibodies in the presence of human cell or serum components at the cellular and subcellular level. This immunoconjugate is not pre-diluted. The optimum working dilution of each conjugate should be established by titration before being used. Excess labelled antibody must be avoided because it may cause high unspecific background staining and interfere with the specific signal. Working dilutions are usually between 1:50 and 1:250; in ELISA and comparable non-precipitating antibody-binding assays between 1:1,000 and 1:8,000.